Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751256AbaDYAxX (ORCPT ); Thu, 24 Apr 2014 20:53:23 -0400 Received: from mga03.intel.com ([143.182.124.21]:63969 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773AbaDYAxV (ORCPT ); Thu, 24 Apr 2014 20:53:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,923,1389772800"; d="scan'208";a="423599544" From: xiao jin To: jhovold@gmail.com, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Cc: juan.zou@intel.com, yanmin.zhang@intel.com, david.a.cohen@linux.intel.com, xiao jin , "Zhang, Qi1" Subject: [PATCH] usb_wwan: some improvement on write and resume Date: Fri, 25 Apr 2014 08:57:15 +0800 Message-Id: <1398387435-13829-1-git-send-email-jin.xiao@intel.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When enable usb serial for modem data, sometimes the tty is blocked in tty_wait_until_sent because portdata->out_busy always is set and have no chance to be cleared. We have found two scenarios lead to portdata->out_busy problem. 1. usb_wwan_write set portdata->out_busy firstly, then try autopm async with error. No out urb submit and no usb_wwan_outdat_callback to this write, portdata->out_busy can't be cleared. 2. usb_wwan_resume run play_delayed() and spin_unlock, but intfdata->suspended still is not set to zero. At this time usb_wwan_write is called and anchor the urb to delay list. Then resume keep running but the delayed urb have no chance to be commit until next resume. If the time of next resume is far away, tty will be blocked in tty_wait_until_sent during time. The patch make some enhancement on write and resume. 1. clear portdata->out_busy if usb_wwan_write try autopm async with error. 2. put play_Delayed and intfdata->suspended together in the spinlock, it's to avoid the write race during resume. Signed-off-by: xiao jin Signed-off-by: Zhang, Qi1 Reviewed-by: David Cohen --- drivers/usb/serial/usb_wwan.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c index 640fe01..8e06afc 100644 --- a/drivers/usb/serial/usb_wwan.c +++ b/drivers/usb/serial/usb_wwan.c @@ -228,8 +228,10 @@ int usb_wwan_write(struct tty_struct *tty, struct usb_serial_port *port, usb_pipeendpoint(this_urb->pipe), i); err = usb_autopm_get_interface_async(port->serial->interface); - if (err < 0) + if (err < 0) { + clear_bit(i, &portdata->out_busy); break; + } /* send the data */ memcpy(this_urb->transfer_buffer, buf, todo); @@ -661,17 +663,15 @@ int usb_wwan_resume(struct usb_serial *serial) } } + spin_lock_irq(&intfdata->susp_lock); for (i = 0; i < serial->num_ports; i++) { /* walk all ports */ port = serial->port[i]; portdata = usb_get_serial_port_data(port); /* skip closed ports */ - spin_lock_irq(&intfdata->susp_lock); - if (!portdata || !portdata->opened) { - spin_unlock_irq(&intfdata->susp_lock); + if (!portdata || !portdata->opened) continue; - } for (j = 0; j < N_IN_URB; j++) { urb = portdata->in_urbs[j]; @@ -684,9 +684,7 @@ int usb_wwan_resume(struct usb_serial *serial) } } play_delayed(port); - spin_unlock_irq(&intfdata->susp_lock); } - spin_lock_irq(&intfdata->susp_lock); intfdata->suspended = 0; spin_unlock_irq(&intfdata->susp_lock); err_out: -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/